The present invention relates to installations for cutting and/or bending metal bars.
In particular, the invention relates to an installation for bending metal bars, particularly bars intended for concrete reinforcement, comprising the characteristics set out in the pre-characterising part of claim 1.
An installation of the aforesaid kind is described and illustrated in the document WO 01/91936. This known installation is provided with transfer means comprising a plurality of pliers of the type specified above, each of which is borne by a slide movable vertically on a carriage which in turn is able to translate along a respective raised cross member. The raised cross members carrying the various pliers are mounted in sliding fashion in the form of overhead travelling cranes on raised longitudinal beams of a fixed support frame. This arrangement is used to transfer bars bent in a bending station from said bending station to a station for collecting the bent bars.
The same arrangement instead is not used, or usable, to transfer the bars still to be bent from a station upstream of the bending station to the bending station. The reason for that limitation stems from the fact that the bars in the station upstream of the bending station are generally aligned in a plane that is not parallel to the plane of lay of the bars in the bending station. A typical case for example is that in the upstream station the bars are mutually side by side in a plane that is horizontal or slightly inclined relative to the horizontal (as in the case of the known device) and that in the bending station the bars must be arranged mutually aligned in a plane that is vertical (as in the case of the known device) or slightly inclined relative to the vertical. On the other hand, the pliers transfer means of the known device constitute a rigid system, in the sense that they are able to draw and deposit the bars set mutually side by side always according to the same orientation of their plane. Because of this limitation, the known device therefore must provide a complex system for transferring the bars from the station upstream of the bending station, which comprises additional transfer devices arranged in series with each other, one of which is dedicated solely to upsetting the bars from the plane in which they lie to the plane in which they must be positioned in the bending station, with the consequent prolongation of the cycle time and risk of overlaps between the bars.